Ablation and Heat Exchange over the Khumbu Glacier

Abstract

The role of supraglacial debris on the abaltion of the Khumbu Glacier was studied based on the observational data of ablation and heat exchange over the glacial surface in the summer monsoon of 1978. The glacier was classified into 4 areas according to the characteristics of supraglacial debris. In the measurement of ablation, a different method suitable for each area was employed. An average ablation rate of 2.5 cm/dy was obtained in the upper half of the ablation area where glacier flow is active, while in the lower stagnant area it is less than 0.4 cm/dy due to a heavy debris load. Short-term heat budget observations have shown that the solar radiation is the main heat source for ablation. The relation between ablation and solar radiation was examined in two areas. Schistose debris with low albedo and thin concentration plays a major role in the enhancement of ablation.